[libcxx-commits] [libcxx] Fix LWG issue4481 disallow chrono::duration<const T, P> (PR #207558)

[A. Jiang via libcxx-commits]

================
@@ -22,6 +22,11 @@
 #include <limits>
 #include <ratio>
 
+#if _LIBCPP_STD_VER >= 26
+#  include <__type_traits/is_same.h>
+#  include <__type_traits/remove_cv.h>
+#endif
+
----------------
frederick-vs-ja wrote:

```suggestion
#  include <__type_traits/is_const.h>
#  include <__type_traits/is_volatile.h>

```
Let's include `<__type_traits/is_const.h>` and `<__type_traits/is_volatile.h>` instead, as `is_const` and `is_volatile` are a bit more expressive (see my suggested change).

https://github.com/llvm/llvm-project/pull/207558